NAIROBI, March 17 (Xinhua) -- Four humanitarian workers kidnapped in Somalia have been released, United Nations humanitarian agency said.

A statement from the Nairobi-based UN Office for Coordination of Humanitarian Affairs (OCHA) issued on Monday night said the aid workers, who were with the United Nations Development Programme and the World Food Programme, were released unharmed.

"I am very enormously relieved that our staff are free and safe. The United Nations is very grateful for the efforts and intervention of the local authorities who used their influence and reach to ensure our dedicated staff was cared for and ultimately released safely and quickly," said UN Resident and Humanitarian Coordinator Mark Bowden.

"This is an important affirmation that the UN presence and its activities in Bakool and the surrounding areas is accepted and protected by the local communities and leaders."

The staff, who were abducted early Monday were in a UN convoy traveling between the UN Compound in Wajid, Somalia, and the local airfield, were comprised of three international staff and one Somali national staff.

The staff members included three expatriate staff working as a nutrition expert for WFP, two UN volunteers working for the UN Development Programme in Puntland. All three were in transit from Puntland to Nairobi on an overnight stop in Waajid. The fourth abducted was a Somali national who was working for the UN Humanitarian Air Service based in Waajid and was taken to act as a translator.

"We managed to secure the hostages unconditionally and without the payment of any ransom for their release," Elder Maollin Alim, one of the local community leaders in Wajid who negotiated for the hostages release told Xinhua.

The commanders of the Islamist insurgent group of Al-Shabaab which controls the town of Wajid were also involved in the efforts to release the hostages.

"The staff taken by a small, independently operating group. Due to the prompt intervention by local authorities, they were released with no one harmed. The incident was not directly targeted at the UN," the UN statement said.

"The quick and positive resolution of this incident will ensure the aid operation can go on unhindered," stated Bowden. "Waajid has been a longstanding aid hub serving relief activities in Somalia."

A number of aid workers and journalists have previously been abducted in the volatile south Somalia where some are being held for ransom.

According to the UN, 35 aid workers were killed in Somalia in 2008 and 26 were abducted. Two workers have been killed this year.

Hundreds of thousands of people are dependent on aid in the war-torn country. Close to 50 percent of the Somali population, or some 3.2 million people, are reliant on humanitarian assistance. One in every seven children is malnourished.

The vast majority of those in humanitarian emergency are in the south and central regions of Somalia.